feat: add dynamic configMap

[d7oc]

• Added configMap which allows to configure all values dynamically in YAML style in the values section which is then transferred to JSON inside a config.php file.
• This solution uses a symlink right now as oC10 cannot lookup subdirectories of the config directory yet. This solution has the downside that on container setup there might be a race condition which will heal itself after sometime. This happens if oC10 tries to read the symlink before the volume it refers to is mounted.

[d7oc]

@xoxys I have removed the if conditions to disable the configMap dynamically. As this will not work right now. If everything is disabled the symlink still points to a file which is not existing and we have no means to delete the symlink again in this case. The only solution I see to fix this is adding a reverse config lookup in oC10.

[xoxys]

I would like to test it a bit more locally.

[xoxys]

I have slightly changed the default behavior:

• configExtra is empty by default now
• an empty configExtra is properly handled to create an empty PHP config snippet